Multi-Ionic Models Of Chloride Diffusion And Migration In Concrete

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Title: Multi-Ionic Models Of Chloride Diffusion And Migration In Concrete

Author(s): Zijian Song; Linhua Jiang; Jinxia Xu; Chuansheng Xiong; Hongqiang Chu; Yan Zhang

Publication: Special Publication

Volume: 305

Issue:

Appears on pages(s): 22.1-22.8

Keywords: Chloride diffusion; Chloride migration; Multi-ionic models; Concrete

Date: 9/1/2015

Abstract:
Diffusion and migration are the two major transport ways of chloride ions in concrete. The single-species models were usually used to predict the chloride diffusion and migration behavior. However, the diffusion and migration processes of chloride ions in concrete are more complicated than expected. The single-species models have obvious limitations in predicting the diffusion and migration processes. In this paper, two multi ionic models are introduced to predict the chloride diffusion and migration processes, respectively. In the diffusion model, the ionic actions and multi-phase reactions are both considered in order to simulate the realistic situations. In the migration model, the ionic actions are also considered while the multi-phase reactions are ignored due to the strong electrical field force applied in the migration test. Besides, a pore structure hypothesis is assumed by a simple deduction to distinguish the migration process from the diffusion process. By considering the factors mentioned above, the governing equations of diffusion and migration models are deduced respectively. In order to verify the multi ionic models, two numerical examples and the verification tests are also conducted. The results show that the multi-ionic models are feasible to predict the chloride diffusion and migration in concrete.